Find the card with equal difference (20 points) C language

Find cards with equal differences (20 branch )

Given N Cards , Write... On the front 1、2、……、N, Then turn it all over and shuffle , Still arranged face down , Write... On the back 1、2、……、N. Subtract the numbers on both sides of each card （ Greatly reduced ）, obtain N A nonnegative difference , Find the card with the same difference .

Input format :
The first line of input gives a positive integer N（2 ≤ N ≤ 10 000）, The next line shows 1 To N A shuffled arrangement of , The first i The number indicates that it is written on the front i The number on the back of the card .

Output format :
Output the repeated difference and the number of repetitions according to the difference from large to small , The format is ：

Difference value Repeat the number

Output one result per line .

sample input :
Here's a set of inputs . for example ：

8 
3 5 8 6 2 1 4 7

sample output :
Here is the corresponding output . for example ：

5 2
3 3
2 2

Code ：

#include<stdio.h> 
int main()
{
    
	int n,i,j,a[10001],b[10001]={
    0};
	scanf("%d",&n);
	for(i=0;i<n;i++)
		scanf("%d",&a[i]);
	for(i=0;i<n;i++)
	{
    
		if((i+1)>=a[i])     // The number on the front is greater than or equal to the number on the back 
			b[(i+1)-a[i]]++;  // Save the difference in the following form b Array 
		else               // The number on the back is greater than or equal to the number on the front 
			b[a[i]-(i+1)]++;
	}
	for(i=10001;i>=0;i--)       // Go back and forth b Array   It's just the difference from big to small 
		if((b[i]!=0)&&(b[i]!=1))    // Find duplicate 
			printf("%d %d\n",i,b[i]);  //i It's the difference  b[i] It's the number of times 
	return 0;
}

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